Liquid level control



May 27, 1941.

J. L. BIACH LIQUID LEVEL CONTROL Filed July 5, 1940 2 Sheets-Sheet 1 INVENTOR L/Z/M Z. 5/40 ATTORNEY May 27, 1941. B|AH 2,243,188

LIQUID LEVEL CONTROL Filed July 5, 1940 2 Sheets-Sheet 2 if it TI 3: iJ Qg/ 30 36 t i: H g

i O-J -z e J0 2 34 53 W J7 19 5% l0 48/ 5! INVVENTOIR 69 LEA A 1 5/601 AITTORNEY Patented May 27, 1941 mourn LEVEL CONTROL John L. Biach, Roselle, N. J., assignor to The Watson-Stillman Co., Roselle, N. 1,, a corporation of New Jersey Application July 5, 1940, Serial No 344,023

4 Claims.

Important objects of the present invention are to provide improved means for automatic control of the level of liquid in a container and, more particularly, for control of the charging of a hydraulic pressure accumulator with liquid against the resistance of compressed air in the accumulator; to provide simple and satisfactory electro-magnetic means for said purpose; to provide for control of liquid level in a container by electro-magnetic means wherein there is a float to rise and fall with the liquid level, an inductance coil is provided to create a magnetic field in the path of the float so that entrance of the float into the field will change inductance in the coil, and there is means responsive to the change of inductance to control chargi g of the container with the liquid; and to pr vide means to prevent crushing of a hollow float employed for said purpose by the fluid pressure in an accumulator.

Other objects oi the invention will'appear here inaiter.

In the drawings, Fig, 1 is a diagrammatic view of a hydro-pneumatic accumulator equipped with the said electro-magnetic level control means;

Fig. 2 is a vertical, sectional view of a portion of the accumulator and the control means and includes a diagrammatic illustration of an electrical system which is responsive to electro-magnetic means for controlling delivery of liquid from a pump to the accumulator and also for limiting discharge of liquid from the accumulator;

Fig. 3 is an enlarged vertical sectional view of the float comprising an element of the control means; and

Fig. 4 is a vertical sectional view showing a modified formof the float, a portion of the tube containing the float, one of the inductance coils to coact with the float, a coil for raising the float to admit air to the interior thereof and a portion of the electrical system provided with means for controlling current in the latter coil.

The invention is illustrated as employed in connection with a hydro-pneumatic accumulator including a closed liquid tank I and a plurality of compressed air tanks 2. The latter are connected in series. An air tank at one end of the series has a pipe connection with the liquid tank near the upper end of the latter, and an air tank at the opposite end of the series has a pipe connection I with an air compressor not shown. A powerdriven pump 4 has a delivery pipe connection 5 with the lower end of the tank I to supply the latter with water. Said pipe has a valve 6 operable to control delivery to the tank. A discharge pipe I leads from the tank. Pipe I has a valve I operable to stop discharge from the tank I when the liquid falls to a certain level in the tank.

ongside of the liquid tank I there is a straight vertical tube 9 closed at its ends. Between the tank and the tube there are pipe connections I0 and I I. Pipe I0 is at a low level and charges the tube with the liquid to the same level as that within the tank. Pipe II is at a high level and charges the portion of the tube above the liquid level with air at the same pressure as the pressure in the tank I, The tube is formed of non-magnetic material such as bronze, for example. Within the tube there is a hollow, metal airtight float I2. In the form shown in Figs. 2 and 3 the float is of tubular form and has closed ends. Its outside diameter is only a little less than the caliber of the tube so that the tube will hold the float substantially upright. In order to give the float suflicient buoyancy its walls are made thin and provision is made for balancing pressure within and without the float to prevent crushing thereof by the high pneumatic and hydraulic pressures.

For that purpose the upper end of the float has an air inlet provided with a downwardly opening check valve I3 and the lower end of the float has an outlet also provided with a downwardly opening check valve I4. These check valves have light springsior holding them normally closed. Compressed air at the top of the float forces open the upper check valve and charges the interior of the float to approximately the same pressure as the pressure upon the outside of the float. Thereby crushing pressure upon the float is adequately resisted. If the pressure outside of the float should diminish to a point below the pressure trapped within the float by the check valve I3 the check valve I4 will be forced open to reduce the internal pressure and restore an approximate pressure balance. The air so forced from the float will carry with it moisture which may have condensed within the float and thus assist in maintaining the buoyancy of the float. The check valve I4 prevents admission of the liquid to the float.

At .points spaced therealong the tube 9 is encircled by inductance coils. In the present instance there are three of these coils supported in fixed positions and including an upper coil I5, a lower coil I6 and an intermediate coil II. coil is supplied with electric current and the coils create magnetic flelds at different levels within the non-magnetic tube. For coaction with the coils the float I2 is provided with a ring II of highly permeable magnetic material such as a material containing iron and nickel, for example.. In the present instance this rln'g is secured within the lower end portion of the float. When, by the rise and fall of the float, said ring is brought into the magnetic field of any one of the coilsit change the inductance in the coil. This change of inductance in the different coils is employed to control the charging of the liquid tank I and also control discharge from the tank through the pipe I.

The coils l5, l and il are supplied with electrical current, preferably alternating, from line wires L and I Two conductors l9 and 20 conmeet the wires L and L respectively to the coil ii. In series with the conductor 55 there is the coil of a relay R. Said coil is located so that the ring l5 oi th'efloat does not enter its magnetic field until the liquid inthe tank and tube approaches a desired maximum level. When the ring is below the effective magnetic field of coil l5 full current flows through the coil of relay R and holds the relay open. When, however, the

ring enters the magnetic field it imposes a resistanoe in'the circuit of coil l5 which causes the relay R to close and establish a circuit including line wire L, conductor 19, a conductor 2!, contactor 22 of said relay, a conductor 23 and line wire L. The coil of a relay R is in series with conductor 23. Relay R has four contactors, 25, 25, 25 and 21. Operation of said relay by closure of relay contactor 22 causes shift of contactor 24 to circuit-closing position and shift of contactors 25, 26 and 21 to circuit-opening position. For cooperation with the relay R there are two relays R and R Relay R has four contactors 28, 29, 30 and Si and relay R has four contactors 32, 33, 34 and 35. When relay R is operated,

as Just described, to close its contactor 24 there is established a sealing circuit for this relay including line wire I conductor 23, a conductor 25', contactor 24, a conductor 36, contactor 28 of relay R a conductor 31, contactor 34 of relay R a conductor 38 and line wire L. When the relay R is so held it keeps the pump 1 idle.

The pump l is driven by an electric motor M. The operating circuit for said motor includes line wire L, a conductor 39, a conductor 48 and line wire L Said circuit is opened and closed by a relay R having two contactors 4| and I2. Relay R is operated through relay R." to open and close the motor circuit. When the float descends, due to withdrawal of liquid from the tank i, and the ring l5 enters the efiective magnetic field of the coil I! it causes starting of the pump to raise the liquid level in the tank. The circuit of coil ll includes line wire L, a conductor 43, a conductor and line wire L. In series with conductor there is the coil of a relay R having a contactor '45. Entrance of ring ll into the magnetic field of coil l'l imposes a resistance in the circuit of the coil and causes contactor 45 to drop and close a circuit for the coil of relay R This circuit includes line wire L, conductor 43, contactor 45, a conductor 45,. and line wire 1?. Thereby the contactors of relay R are raised. Raising oi contactor 25 breaks the holding circuit of relay R and permits the contactors thereol to drop. Dropping of oontactor 25 establishes for relay R. a holding circuit including line wire L, aconductbr l'l, contactor 25, a conductor 48, oontactor 35 of relay R, 'a conductor 45, contactor 25 of relay R, a. conductor 5|, conductor liandlinewireh'. Atthe sametimacontactor' llotrelaymcloeesthecircuitofthepumpmotor tactor 42 closes the motor circuit and contactor 4| establishes for relay R a holding circuit including line wire L, a conductor 55, contactor 21 of relay R, a conductor 55, contactor ll, a conductor 51, conductor 54 and line wire L Thereby the pump motor circuit is held closed by contactor ll and the pump is operated until the ring l8 oi the float enters the magnetic field of the upper coil l5. As previously described, that causes closure of the circuit for the relay R and the contactors of said relays are raised. Raising oi contactor 21 breaks the holding circuit for relay R so that the contactors 01' said relay drop and the circuit for the pump motor is opened.

Ii, for some reason, the liquid level in tank I should drop sufiiciently to allow the ring II of the float to enter the magnetic field oi the lower coil IS the discharge valve 8 will be closed automatlcally to prevent further loss of liquid from.

circuit includes line wire L, conductor 58, a conductor 6i, contactor 50, a conductor 62, a conductor 53 and line wire LP. Thereby the contactors of relay R are raised. Raising of contactor 32 establishes for relay R a holding circuit including line wire L conductor 53, conductor 52, a conductor 54, contactor 32, a conductor 55, contactor 30 of relay R a conductor 56, contactor 2501? relay R, a conductor 51 and line wire L. It will be understood that said contactors of relays R and R will be in their lower positions to make this holding circuit by reason of the fact that descent of the ring is into the field oi coil ll will have caused closing of the circuit of relay R and consequent breaking of the holding circuit of relay R and further descent of the ring 18 into the field of coil l5 will have caused operation of relay R to break the circuit of relay R.

The discharge valve 8 is normally held open by a spring 88. A solenoid 69 is provided for closing the valve. when the relay R is operated as just described it causes its contactor 33 to establish tor the solenoid a circuit including line wire L, a conductor 10, contactor 35, a conductor II, the winding of the solenoid, a conductor 12, and the line wire L. Thereby the solenoid will be operated to close the valve 5 and hold it closed as long as the holding circuit for the relay R remains closed. Subsequent rise of the ring ll 01' the float into the magnetic field of the coil II will cause operation of the relay R. to break the holding circuit for relay R Thereupon the con- I tactor 32 of the latter relay will drop and break one ofthe inductance coils, preferably the upper coil ll. Directlyabovecoil llalargerooil'll encirclesthefloattocreatewithinthetubela more powerful fleld capable of lifting the float entirely out of .the liquid in the tube so that compressedaircanenterthefloateachtimethatthe float reaches a certain elevation in the tube. Thereby any loss of air from the float by absorption into the liquid is compensated for and the float is prevented from sinking.

The lifting coil I8 is supplied with current by a circuit including line wire L, a conductor 14, a switch II, a conductor 10, a conductor l1 and line wire 1?. Switch II is controlled by a timer II which may be of any of several well-known types. There is provided for starting the timer a circuit including line wire L, a conductor ll, an additional contactor Oil provided in the relay R, a conductor II, a conductor I! and line wire I). When the contactors of relay R are raised, as previously described, in response to entrance of the ring ll of the float into the gnetic fleld of coil i5, raising of contactor 80 will close the circuit for starting the timer. The timer will then close switch I! to supply the coil 18 with current for a brief period during which the magnetic fleld created by coil 18 will raise the float clear of the liquid. Then the timer will cause the switch II to shift and open the coil circuit. The float will then drop back to submerge its open lower end in the water. While a lifting coil is shown associated with only one of the three original coils there may, if desired, be a lifting coil associated with each of said three coils.

What I claim is:

1. "In combination with a tank to contain liquid and means to supply said tank with liquid, the tank having a discharge connection, a vertical tube of non-magnetic material in communication with the tank to contain a column of said liquid for rise and fall of the level thereof along with the rise and fall of the liquid level in the tank, a float within the'tube to rise and fall with the rise and fall or the level of the liquid of said column and having magnetic material in its structure, a plurality of inductance coils encircling said tube and supported at points spaced therealong and including an upper coil, a lower coil and an intermediate coil, each having electrical connections to supply it with current and all being arranged to dispose their magnetic flelds at spaced tical tube of non-magnetic material in communication with the tank to contain a column of said liquid with said compressed air thereon, for rise and fall of the liquid level of the column along with the rise and fall of the liquid level in the tank, a hollow float within the tube to rise and fall with the rise and fall of the level of the liquid of said column and having magnetic material in its structure, said float being pen at its lower end for trapping air therein, for the purtube and supported at a point therealong to dispose its magnetic fleld within a predetermined range of rise and fall of the float and having connections to supply it with current, for change of inductance in said coil by entry of the magnetic material of the float into said fleld, means responsive to such inductance change to control delivery from said liquid supply means to the tank, and an inductance coil encircling the tube and supported at a point above said first coil and having connections to supply it with current, for action by the current in said second coil upon the magnetic material of the float to lift the float from the liquid in the tube for admission of air to the interior of the float.

3. In combination with a tank to contain liquid and compressed air on the surface of the liquid and means to supply said tank with liquid, a vertical tube of non-magnetic material in commimication with the tank to contain a column of the liquid with said compressed air thereon for rise and fall of the liquid level of the column along with the rise and fall of the liquid level in the tank, a hollow float within the tube to rise and fallwith the rise and i'ail of the level of the liquid oi" said column and having magnetic material in its structure, said float being open at its lower end for trapping air therein, for the purfloat at one position along the tube to control delivery from said liquid supply means to the tank,'and an inductance coil encircling the tube levels within a predetermined range of rise and fall of said float, for change of inductance in any one of said coils by entry of the magnetic material of the float into the magnetic fleld of the coil, means responsive to such inductance change in the upper coil to stop delivery from said liquid supply means to the tank, means responsive to such inductance change in the intermediate coil to cause delivery from said supply means to the tank, and means responsive to such inductance change in the lower coil to prevent delivery from the tank through said discharge connection.

2. In combination with'a tank to contain liquid and compressed air on the surface of the liquid and means to supply said tank with liquid, a verfloat within the tube to rise and fall with the level of the liquid of said column and having magnetic material in its structure, said float being open at its lower end to trap air therein, for

the purpose set forth, electrical circuit means,

means operable by arrival of the float at a position along the tube to control current in said circuit means, and electrical means outside of the tube to create a magnetic fleld within the tube at a point along the latter to lift the float from the liquid when the magnetic material of the float enters said fleld, for admission of air to the interior of the float.

JOHN L. BIACH. 

